title: Effect of different degrees of hypothermia on myocardium in treatment of hemorrhagic shock.
abstract: The use of hypothermia in cardiac and neurologic surgery is well established, but its use in treating hemorrhagic shock is controversial. Using a modified Wiggers hemorrhagic shock model, we examined the effects of hypothermia (group 1, 33 degrees C, N = 7; group 2, 28 degrees C, N = 12) after inducing hemorrhagic shock. In group 3, N = 6, dogs were maintained at body temperature in hemorrhagic shock and throughout resuscitation (normothermic shock). Sixty minutes after resuscitation (shed blood and lactated Ringer's solution, 50 ml/kg body wt), all hypothermic dogs were rewarmed and studied for an additional 120 min. Comparison of moderately hypothermic, severely hypothermic, and normothermic dogs showed a lower heart rate (80.6 +/- 3.3, 62.5 +/- 4.1, and 136.7 +/- 4.2 beats/min, P less than 0.05), reduced rate of left ventricular pressure fall (938 +/- 125, 700 +/- 75, and 1550 +/- 275 mm Hg/sec, P less than 0.05), a lower arterial pH (7.15 +/- 0.02, 7.10 +/- 0.03, and 7.24 +/- 0.02, P less than 0.05), a lower respiratory rate (18 +/- 1, 14 +/- 1, and 24 +/- 2 breaths/min, P less than 0.05), and a higher arterial pCO2 (36.6 +/- 1.6, 46.9 +/- 4.6, and 20.3 +/- 2.0 mm Hg, P less than 0.05). Left ventricular end-diastolic pressure was lower in the severely hypothermic dogs while stroke volume was higher in this group. Rewarming ablated all differences in cardiovascular performance and acid-base balance. Our data show that moderate hypothermia during hemorrhagic shock increased coronary perfusion, enhanced cardiac contractile performance, and significantly reduced myocardial oxygen requirements.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Surgery, University of Texas Southwestern Medical Center, Dallas 75235-9031.
authors.forename: D M
authors.initials: DM
authors.lastname: Meyer
authors.forename: J W
authors.initials: JW
authors.lastname: Horton
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D003326:Coronary Circulation; D004285:Dogs; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D007036:Hypothermia, Induced; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D012771:Shock, Hemorrhagic / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*